Although mean blood lead (BPb) levels in the United States continue to decrease, there is evidence that certain populations, particularly young children living in communities with a high proportion of older, poorly maintained housing, remain at high risk for lead exposure. The objective of this study was to describe and compare the prevalence rates of elevated childhood BPb levels in relatively small geographic areas within seven U.S. cities. Data on the number of children who received BPb tests and the number of children identified with elevated BPb, by ZIP code, were collected from state or local health departments. The number of children younger than 6 years of age living in each ZIP code was extracted from the 1990 U.S. census. The study calculated the city-wide mean percent of children with elevated BPb levels for each city and compared these to the percent of children with elevated BPb levels, by ZIP code, within the same city. Findings indicated that 19.5 percent of the children tested in the 7 cities had elevated BPb levels. In each city, most of the children with elevated levels were concentrated in relatively few ZIP codes. In six of the cities, 50 percent of the children lived in fewer than 25 percent of the ZIP codes. Rates of elevated levels at the ZIP code level ranged from below the national average to more than 10 times higher. (Contains 13 references.) (EV)